Kininogen-1 and insulin-like growth factor binding protein-6 as serum biomarkers for proliferative vitreoretinopathy

Abstract

To evaluated the predictive potential of kininogen-1 and insulin-like growth factor binding protein-6 (IGFBP-6) for PVR. Vitreous and serum samples were obtained from 24 PVR patients. Vitreous from 8 donated normal eyes, and serum samples from 20 healthy volunteers served as control. Patients who underwent vitrectomy with C(3)F(8) gas tamponade (n = 15) and silicone tamponade (n = 8) and patients who experienced recurrent retinal detachment after scleral buckling surgery (n = 8) were recruited for serum tests as well. Western blot analysis was employed to detect the presence of kininogen-1 and IGFBP-6. The protein concentration was measured by using enzyme linked immunosorbent assay (ELISA) analysis. All date were analyzed with the SPSS 3.0 for Windows (only-way analysis of variance and t test). Western blot analysis displayed that except that IGFBP-6 was absent in 2 PVR vitreous, both kininogen-1 and IGFBP-6 were otherwise found in all PVR vitreous and serum samples. Neither kininogen-1 nor IGFBP-6 can be detected in normal vitreous or serum samples. Protein expression was more intensive in severe PVR vitreous than in mild PVR vitreous, which was confirmed by a significantly higher concentration of each protein in sever PVR vitreous. The ELISA outcomes documented that kininogen-1 concentration in vitreous were significantly higher in severe PVR patients than those in mild PVR (281.0 ± 63.0 & 237.5 ± 32.1) µg/L (t = 5.44, P < 0.05). Kininogen-1 was about 2 times higher in serum than in vitreous (443.3 ± 190.1) µg/L (t = 5.27, P < 0.05). At 6 months after vitrectomy with gas tamponade in 15 patients, their kininogen-1 level in serum was significantly lower than that of preoperation (81.9 ± 18.6 & 443.3 ± 190.1) µg/L (t = 5.26, P < 0.05) and encircling failure group was (116.8 ± 45.1) µg/L, it was higher than that of normal and silicone tamponade groups (t = 3.95, 4.34;P < 0.05). Similarly, IGFBP-6 concentration in vitreous were significantly higher in severe PVR patients than those in mild PVR (352.9 ± 64.4 & 283.9 ± 69.9) ng/L (t = 5.08, P < 0.05) and its level in serum was (185.3 ± 34.9) ng/L and lower than that of in vitreous(t = 7.95, P < 0.05). At 6 months after vitrectomy with gas tamponade in 15 patients, their IGFBP-6 level in serum decreased comparing that of preoperation (65.4 ± 31.8) ng/L (t = 11.10, P < 0.05) and encircling failure group was (109.2 ± 6.6) ng/L, it was higher than that of normal and silicone tamponade groups (t = 3.16, 2.77; P < 0.05). Kininogen-1 and IGFBP-6 are presented in serum and vitreous in PVR patients. The strength of protein expression is related to the severity of PVR. These results suggested that kininogen-1 and IGFBP-6 can be biomarkers for severe PVR.